Considerable effort has been devoted over the years to the provision of oil-soluble additive formulations for use in automatic transmission fluids. Many such fluids and additive formulations are available as articles of commerce, and the literature contains many references to suitable compositions of this type. See for example U.S. Pat. Nos. 3,311,560; 3,450,636; 3,578,595; 3,630,918; 3,640,872; 3,775,324; 3,779,928; 3,933,659; 3,974,081; 4,018,695; 4,036,768; 4,116,877; 4,263,159; 4,344,853; 4,396,518; and 4,532,062.
Although friction-reducing additives of various types have been proposed and used in automatic transmission fluids, their effectiveness generally diminishes with time, probably because of oxidative and thermal degradation of the additives during use.